A development is being made for current interruption device that cuts off current flowing between electrode terminals (a positive electrode terminal and a negative electrode terminal) when an electricity storage device is overcharged or when a short circuiting occurs therein. The current interruption device is arranged between an electrode terminal and an electrode (between a positive electrode terminal and a positive electrode, or between a negative electrode terminal and a negative electrode). Japanese Patent Application Publication No. 2012-38529 discloses a current interruption device that fixes a first conducting member (caulking part) to a casing and arranges a second conducting member (power collecting terminal) at a position opposed to the first conducting member. Hereinbelow, Japanese Patent Application Publication No. 2012-38529 will be termed Patent Reference 1. An end portion of a deforming member is fixed to the first conducting member. A center portion of the deforming member is in contact with the second conducting member. An end portion of the deforming member is in contact with the second conducting member via an insulator (internal lower gasket). When the center portion of the deforming member is in contact with the second conducting member, the first conducting member and the second conducting member are configured to be conducted, and the first conducting member and the second conducting member are nonconducted when the center pardon of the deforming member separates away from the second conducting member. In the current interruption device of Patent Reference 1, the center portion of the deforming member separates away from the second conducting member when pressure inside the electricity storage device exceeds a predetermined value, and the conduction between the electrode terminal and the electrode is interrupted by bringing the first conducting member and the second conducting member to be nonconducted.